An elite law enforcement team is battling foreign drug cartels operating in Northern California, and the ABC7 I-Team has stunning video. The cartels wreak havoc on the environment and produce pot tainted with toxic chemicals; they are not medical marijuana growers trying to do it right.

No matter what happens with the vote to legalize marijuana, law enforcement sources tell the I-Team the drug cartels will continue to be a serious problem. They pose threats on several fronts.

It's dawn on the Delta. The Department of Fish and Wildlife's special ops unit, and the Marijuana Enforcement Team infiltrates a Mexican drug cartel's marijuana grow.

A signal - a game warden hears someone talking and they land.

1st Game Warden says: "Nothing's going to be good."

2nd Game Warden replies: "This is good and thick swamp land."

They make their way to the grow site and make arrests. Their tracking dog, Phebe, takes down a suspect.

Lt. John Nores, head of the Marijuana Enforcement Team, explains, "That's apprehension bite number 113 in her very long career."

They find thousands of plants, pot drying, and the camp where the workers lived.

Dan Noyes asks: "Who are they and where are they from?"

Nores answers by saying: "A majority of the outdoor trespass growers, not all of them, but a majority of them are from south of our border. California is the epicenter for marijuana cultivation, one of only six true Mediterranean climates in the entire world. It's possible to grow marijuana very effectively here and the organized crime cartels know that as well."

Nores takes video of the raids, and gave some to the I-Team.

At an estimated 2,000 to 4,000 grows across California, the cartels bring in toxic chemicals that are banned here. They block streams, dump fertilizer, weed, insect and rat killer into the water that flows to the plants through plastic piping.

"Those toxics on one marijuana site as an example are killing up to five to 10 miles of creek and every living thing in the creek," Nores said.

They set out poison to keep animals away from the crops.

Nores pointed out dead animals at one cartel marijuana operation saying: "Another rabbit looks like it barely made it out of the grow, which is just right there."

The head of the Marijuana Enforcement Team has documented the deadly aftermath - rabbits, grey fox, a mountain lion, which were all poisoned. A cartel suspect posed with a poisoned golden eagle. Then, there's the case of a 300-pound mother bear that died after eating poison set out in cans of tuna.

Nores told Noyes, "Her little 50 pound baby cub had ingested some of it as well, saw the mother bear expire, was very confused and obviously terrified, climbed up in a tree and died in the V of the tree, of two branches just about 10 feet above her mother."

The threat to hikers, hunters and anglers is serious. Nores tells the I-Team he has found six pungi pits, sharp sticks concealed by leaves, leading to grow sites in the past year. And the raids have found growers that are heavily armed.

A game warden got shot through both legs with an AK-47, during a raid on a cartel grow in the mountains above Los Gatos in 2005. Nores tells Noyes the team has had a total of five shoot-outs since then.

He credits Phebe with preventing many others, as seen in exclusive video of the raids. The team now includes a sniper - they will not be out-gunned again.

"The days of going in with a small team when you might encounter many armed gunman that are trying to defend their multi-million dollar cash crop are gone," Nores said.

Fish and Wildlife has only an 11-man unit to cover the entire state. They do work with local law enforcement and other agencies, but it's just too much to handle with thousands of organized crime grows on public land.

"We don't want 'em in our woods," Nores said. "We don't want 'em to harm our public, and I don't want to see 'em destroying our wildlife and our waterways any more than they already are, so that's our main motivation to keep doing it and we really enjoy stopping the environmental crime on every level we can."

The cartel grows consume millions of gallons of water, which is especially bad in a drought. Most of their marijuana winds up on the East Coast, where it can bring in much more than it can in this state. Simple supply and demand.